Use the NUL Port for Testing

The NUL port is generally used for testing network printing. Set a printer to use the NUL port and pause it (so you can see jobs waiting; otherwise the jobs pass through the port too fast to watch them). Then send a job to that printer from a connected client. You should be able to see the job when you open the printer object. If you don't see the job, check the setup to make sure the printer is configured for the NUL port. If you do see the job, your test is successful. Resume printing, which really does nothing because jobs sent to a NUL port just disappear. Instead of paper, documents print to thin air as they travel to lost document la-la land.

To use the standard port monitor, the print server must be running the TCP/IP protocol (since this is the default networking protocol for Windows Server 2003, this shouldn't be a problem).

IP^I Although clients are usually running TCP/IP in a Windows 2000 or Windows

Server 2003 domain, it's not necessary for clients to run TCP/IP in order to print to a network printer via a print server that's using the standard print monitor. After all, only the print server needs to communicate with the printer. Clients can run any common transport protocol to communicate with the print server.

The standard port monitor sends documents to printers via one of two print server protocols: RAW or LPR. Between them, those protocols cover the communication requirements for almost all TCP/IP network printers.

For most network printers, the RAW print server protocol is the default communication type. The print server opens a TCP stream to one of the printer's ports (usually 9101 for LPT1,9102 for LPT2, and so on). The print server disconnects from the port when it has finished sending the data. However, if necessary (meaning, if the printer requires it), you can configure the standard port monitor to use LPR.

¬ęThe standard port monitor does not conform to the RFC 1179 requirement that the source TCP port lie between port 721 and port 731, because that limits the print server to managing 11 printers. Therefore, the Windows Server 2003 standard port monitor uses ports from the unreserved pool of ports (which are ports 1024 and above).

To add a port that uses the standard port monitor, follow these steps:

1. Open Printers and Faxes.

2. Right-click the network printer you want to configure, and choose Properties from the shortcut menu.

4. Click the Add Port button and select Standard TCP/IP Port from the list of available port types.

Printei Poris

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  • bucca
    What is nul port used for in windrows?
    7 years ago

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